Fans of the world's favorite teen wizard have a particular reason to be itching for the next installment. It's been two years since a "Harry Potter" movie hit theaters, the longest interval since Warner Bros . began churning them out in 2001.

Part six, " Harry Potter and the Half-Blood Prince ," arrives this summer after a surprise delay, when the studio bumped it from its original slot last November.

"Half-Blood Prince" has Harry (Daniel Radcliffe) charged with unlocking secrets from the noggin of a new teacher ( Jim Broadbent ), information vital to the young wizard's ongoing battle with the evil Voldemoort.

Meantime, Harry struggles to get on with the usual teenage pressures of school, social activities and budding romance.

"We've got some really playful sequences and some material that obviously dips into the darker world of `Potter,'" director David Yates said. "As the series matures, it tonally does get darker overall. It's sort of inevitable as you follow the material. The kids are getting older, more mature and complex."

Getting younger are the heroes of another otherworldly summer franchise. James Kirk, Spock and the rest of the Enterprise crew return in "Star Trek," a relaunch of the series featuring an all-new cast (though Leonard Nimoy is on hand to play the older Spock).

Director J.J. Abrams takes the sci-fi series back to its roots, explaining how the gang of interstellar explorers came together in the first place.

"For Kirk and Spock, it's charting their lives to a small extent from boyhood and their first encounter, which is a bit contentious, to kind of the beginning of the relationship we all know," said Chris Pine , who plays Kirk, the dashing Starfleet officer originated by William Shatner , opposite Zachary Quinto as the younger Spock.

"They are at odds at first. The conflict of the relationship actually gives Zachary a couple moments where he's not as controlled and rational as Mr. Nimoy's character was. He has a couple of outbursts that aren't exactly the classic Spock."